To enter a redemption code on eBay, click the Pay Now button, select a shipping option, and then enter the code in the Redeem a Gift Card, Certificate or Coupon box. As of 2015, this box is located just above the subtotal and shipping cost information.
After entering or copying and pasting the code, hit the Apply button to generate the new price. Next, log in to your PayPal account, select a method of payment, and then confirm the payment to complete the transaction. You are limited to using one redemption code per transaction, and the items purchased must meet all of the requirements to use the code.